Polyphenylene ether has the disadvantages of being poor in fluidity and impact resistance while excellent in heat resistance, and mechanical and electrical properties. It is known that in order to eliminate the above disadvantages of a polyphenylene ether, a rubber-modified alkenylaromatic polymer compatible with the polyphenylene ether is compounded. In polyphenylene ether compositions with such rubber-modified alkenylaromatic polymer compounded thereto, however, if the rubber content is increased to improve their impact resistance, the fluidity and gloss of the compositions will be considerably decreased.
Various attempts have been made to improve the balance among fluidity, gloss and impact resistance of compositions comprising a polyphenylene ether and a rubber-modified alkenylaromatic polymer. For example, Japanese Laid-Open patent application Nos. 84852/83 and 131051/80 disclose a method of improving the fluidity of compositions comprising a polyphenylene ether and a rubber-modified alkenylaromatic polymer by compounding thereto a mineral oil or a low molecular weight polyolefin. Japanese Laid-Open patent application No. 194947/83 discloses a method of improving the impact strength of compositions comprising a polyphenylene ether and a rubber-modified alkenylaromatic polymer-by compounding thereto a carbonyl or hydroxyl group-containing ethylenic copolymer. It has been revealed, however, that the above methods improve fluidity, gloss and impact strength to some extent, but fail to sufficiently improve the balance among them.